The invention relates to a Pelton runner with a wheel disk and separately fabricated buckets, which may be cast or made from a solid block of material and secured detachably to the wheel disk, fastened by at least one screw or at least one bolt.
There are several different processes for manufacturing Pelton runners. One laborious method is to form the Pelton buckets from a solid blank, causing approximately 60-70% of the material to be lost. In other processes for making Pelton turbines, such as HIWELD™, MICROGUSS™ and shown in EP 960181, buckets are welded onto suitably prepared wheel disks. In addition, a method is described in GB 174,768 and CH 111442, where individual buckets are secured to suitably shaped parts of a wheel disk by means of axial bolts. To be stable, the buckets must be provided with suitable extensions through which the bolts can be inserted, and the wheel disk must also have corresponding extensions.
The methods used so far are very laborious and cost-intensive as they require special designs of devices for welding or bolting on, among other things. Erosion damage to integrated Pelton runners, which are formed in a single piece or where the buckets are welded on using various methods, is usually repaired by welding and grinding down. This presents a substantial risk, especially in the high-stress zone at the base of the bucket because cracks, which then result in subsequent breaks, can begin here.